The use of industrial-rated circuit breakers within lighting panelboard and switchboard enclosures connected with industrial equipment sometimes requires that the circuit breaker handles be locked in an ON or OFF position to prevent inadvertent opening or closing of the circuit breaker contacts. This is especially important when electrical equipment is turned OFF for maintenance and repair purposes and the electrical equipment is visually remote from the panelboard or switchboard enclosure. When such a circuit breaker is locked in an ON position, it is important that the circuit breaker be allowed to trip to interrupt the circuit through the protected equipment upon the occurrence of an overcurrent condition. U.S. Pat. No. 4,300,030 describes a circuit breaker handle blocking attachment that allows the circuit breaker to move to a TRIPPED position. A tool such as a screwdriver is required for mounting and dismounting the handle blocking attachment from the circuit breaker handle.
To ensure that the circuit breaker handle remains in the ON or OFF position, a circuit breaker handle interlock such as described in U.S. patent application Ser. No. 481,012 filed Feb. 16, 1990 entitled "Circuit Breaker Handle Interlock Arrangement" is employed. In order to change the position of the circuit breaker operating handle, the padlock must be unlocked and removed from the handle interlock.
With most state-of-the-art circuit breaker operating handle interlock and blocking arrangements, it is difficult to ascertain the position of the underlying circuit breaker operating handle to determine whether the circuit breaker contacts are in their "OPEN", "CLOSED" or "TRIPPED" positions. U.S. Pat. No. 4,796,154 describes a circuit breaker contact status indicating handle wherein a visual access slot next to the circuit breaker operating handle indicates immediately to an observer the condition of the circuit breaker contacts by the use of appropriately colored indicia. This patent is incorporated herein for purposes of reference.
One purpose of the invention accordingly, is to provide a simple and economical means for preventing either inadvertent or intentional operation of the access to the position of the operating handle. A further purpose of the invention is to provide a circuit breaker operating handle blocking means which allows the circuit breaker operating handle to be set at its ON or OFF position without interfering with the travel of the operating handle to its TRIPPED position.